Labeled fusion protein

Abstract

The present invention aims at providing a general-purpose experimental tool which specifically binds to a macromolecular substance that will be a receptor for a specific ligand such as drug, and is applicable throughout various processes to explore the nature of the macromolecular substance. In order to achieve this object, a molecular module has been developed which binds to a target compound and is used for purifying or labeling the target compound, wherein the molecular module has a rod-like spacer substance, an interacting substance that interacts with the target compound, a tag and a labeling substance, the interacting substance being positioned at one end of the rod-like spacer substance, and the tag and the labeling substance being positioned at the other end of the rod-like spacer substance.

Description

TECHNICAL FIELD

The present invention relates to a molecular module for purifying or labeling a target compound; a tag and a label-fused protein based on the molecular module; and a method of protein purification using the molecular module.

BACKGROUND ART

In order to explore the nature of a molecule that could be a receptor for a specific ligand (such as physiologically active substance, drug or antibody that acts upon binding to a cell composing, macromolecular component, e.g., protein or nucleic acid), usually, several techniques selected from various existing technologies are used in combination. For example, various techniques such as a technique of identifying an unknown receptor by such as photoaffinity labeling using a drug derivative or the like as a ligand; a technique of the intracellular localization of the receptor; a technique of isolating/purifying the receptor and examining its nature; or a technique of elucidating the binding site within the receptor (complex) molecule with a higher spatial resolution must be used jointly as the purpose demands. Even when one ligand is to be investigated, it is necessary to prepare separately a number of ligand derivatives suitable for individual techniques, which imposes a tremendous burden.

As a method of identifying those components to which a specific drug binds, affinity labeling is known. In this method, a ligand derivative to which a fluorescent dye or radioactive isotope has been added is photo-crosslinked to a target. Subsequently, information such as the molecular weight or amino acid sequence of the resultant labeled molecule is obtained using electrophoresis or various chromatographies.

For isolation and purification of a substance which will be a target binding partner for a ligand (such as receptor), a series of techniques called affinity purification is often used. When the target is a protein or a complex thereof, the classical chromatography is usually used in which resin beads immobilizing a ligand by covalent bond are packed in a column; a raw solution containing the target material is applied to the column; and the bound fractions alone are dissociated and eluted. However, when the target is a large-sized membrane fraction or non-adherent cell each of which is difficult to apply to the column, a batch method is also used in which similar resin beads or magnetic beads are utilized to collect the target substance by centrifugation or magnetism. In particular, when a target substance is to be separated after binding to a protein that is embedded in the membrane (such as intracellular organelle or non-adherent cell), a ligand directly immobilized on the surfaces of resin or magnetic beads is difficult to contact the target substance in many cases. In order to solve this problem, a spacer consisting of long straight carbon chain is inserted between the beads and the ligand. However, when a long carbon chain is used, hydrophobicity often increases. This makes it highly possibility that the binding of the target substance by the ligand does not necessarily reflect their specificity. For alleviation of this problem, it is desirable to use a spacer capable of always retaining a long distance.

On the other hand, in order to microscopically indicate the intracellular or extracellular localization site of a ligand-binding protein, a part or the whole of the protein prepared by a biochemical or molecular biological technique is used to prepare a specific antibody. Then, the localization (site) of the protein is elucidated by immunofluorescence or immunoelectron microscopy using the antibody. Further, for searching the binding site within the target molecule (complex), conventionally, structural data are collected by those means capable of obtaining atomic resolution, e.g., purifying and crystallizing the receptor/ligand complex and subjecting the crystal to X ray diffraction.

Although comprehensive methods to explore a large number of materials have been invented (e.g., use of robots), basically, researchers have no choice but to combine these techniques and proceed step by step in order to achieve their initial purpose. Regardless of what processes are employed, it is necessary to prepare individual ligands suitable for selected techniques. This always imposes a considerable burden in terms of labor, time and cost.

[Patent Document 1] Japanese Unexamined Patent Publication No. 2005-291836

DISCLOSURE OF THE INVENTION

Problem for Solution by the Invention

Under the above-described circumstances, a convenient material which does not affect the specific affinity between ligand and receptor and thus can be used throughout all the exploring processes will be able to reduce the above-mentioned burden greatly. It is desired to make full use of protein engineering or organic chemistry to thereby develop a general-purpose protein module that can be used for such a purpose. In reply to this demand, the present invention aims to provide a general-purpose experimental tool which specifically binds to a macromolecular substance that will be a receptor for a specific ligand such as drug, and is applicable throughout various processes to characterize the properties of the macromolecular substance.

Means to Solve the Problem

As a result of extensive and intensive researches toward the solution of the above-described problem, the present inventors have found that by adding to a target compound to be explored a tag and a label through a rod-like spacer substance, it is possible to give a molecular module a form suitable for wide-ranged exploration techniques (such as identification, isolation, microscopic observation, etc.) without altering the nature of the target compound.

It is also possible to add a tag and a label directly to a target substance. For example, the following methods may be contemplated; a method in which the target compound to be explored is fused to a tag and a label, and a method in which a substance with affinity for the target compound is added to both tag and label, and the resultant tag and label are bound to the target compound. However, the former method involves a possibility that the insertion of tag and label may destroy or alter the conformation of the target compound, resulting in the loss of the inherent nature of the target compound. In the latter method, the label and the tag may not bind to the target compound well due to steric hindrance of the target compound or compounds adjacent thereto. Even when the label and the tag could bind to the target compound, they may not be sufficiently exposed from the surface to the target compound, resulting in insufficient function as a tag and a label.

The present invention has been achieved based on the above-described findings.

The present invention provides the following (1) to (14).

(1) A molecular module which binds to a target compound and is used for purifying or labeling the target compound, wherein the molecular module has a rod-like spacer substance, an interacting substance that interacts with the target compound, a tag and a labeling substance, the interacting substance being positioned at one end of the rod-like spacer substance, and the tag and the labeling substance being positioned at the other end of the rod-like spacer substance. (2) The molecular module according to (1), wherein the rod-like spacer substance, the interacting substance, the tag and the labeling substance form a polypeptide chain. (3) The molecular module according to (1) or (2), wherein the rod-like spacer substance is a protein that takes an antiparallel coiled coil structure or a protein that takes a spectrin repeat structure. (4) The molecular module according to any one of (1) to (3), wherein the tag is a histidine tag or a biotin acceptor peptide. (5) The molecular module according to any one of (1) to (4), wherein the labeling substance is GFP or DsRed. (6) A tag and a label-fused protein having a protein body, a rod-like spacer substance, a tag and a labeling substance, wherein the protein body is positioned at one end of the rod-like spacer substance, and the tag and the labeling substance are positioned at the other end of the rod-like spacer substance. (7) The tag and label-fused protein according to (6), wherein the protein body, the rod-like spacer substance, the tag and the labeling substance form a polypeptide chain. (8) The tag and label-fused protein according to (6) or (7), wherein the rod-like spacer substance is a protein that takes an antiparallel coiled coil structure or a protein that takes a spectrin repeat structure. (9) The tag and label-fused protein according to any one of (6) to (8), wherein the tag is a histidine tag or a biotin acceptor peptide. (10) The tag and label-fused protein according to any one of (6) to (9), wherein the labeling substance is GFP or DsRed. (11) A method of protein purification comprising the following steps: (i) a step of expressing a fusion protein-encoding DNA in a cell, wherein the fusion protein has a protein body, a rod-like spacer substance, a tag and a labeling substance, the protein body being positioned at one end of the rod-like spacer substance, and the tag and the labeling substance being positioned at the other end of the rod-like spacer substance; (ii) a step of disrupting the cell and contacting the resultant homogenate with a substance having affinity for the tag; and (iii) a step of collecting the fusion protein bound to the substance having affinity to the tag. (12) The method according to (11), wherein the rod-like spacer substance is a protein that takes an antiparallel coiled coil structure or a protein that takes a spectrin repeat structure. (13) The method according to (11) or (12), wherein the tag is a histidine tag or a biotin acceptor peptide. (14) The method according to any one of (11) to (13), wherein the labeling substance is GFP or DsRed.

Effect of the Invention

Conventionally, for exploring the properties of a substance, it was necessary to convert a target substance into a form suitable for each of the exploring techniques selected. However, by using the molecular module of the present invention, it becomes possible to omit such complicated operations.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a schematic diagram of the molecular module of the present invention (A) and a schematic diagram of the tag and label-fused protein of the present invention (B).

FIG. 2 shows the amino acid sequence (SEQ ID NO:1) of a fusion protein comprising a protein based on the stalk domain of dynein having a mutation introduced thereinto (a short-type protein of rod-like spacer structure is used; hereafter, a protein of this type is referred to as the "short type"), a histidine tag, a biotin acceptor peptide and GFP. The portion marked with a single underline is GFP; the portion marked with a double underline is the biotin acceptor peptide; the portion marked with a dotted underline is the histidine tag; the portions enclosed with boxes are linkers; and the portions without any marking represent the dynein protein whose stalk domain has been mutated.

FIG. 3 shows the amino acid sequence (SEQ ID NO:2) of a fusion protein comprising a protein based on the stalk domain of dynein having a mutation introduced thereinto (short type), a histidine tag, a biotin acceptor peptide and DsRed. The portion marked with a single underline is DsRed; the portion marked with a double underline is the biotin acceptor peptide; the portion marked with a dotted underline is the histidine tag; the portions enclosed with boxes are linkers; and the portions without any marking represent the dynein protein whose stalk domain has been mutated.

FIG. 4 shows the amino acid sequence (SEQ ID NO:3) of a fusion protein comprising a protein based on the stalk domain of dynein having a mutation introduced thereinto (a long-type protein of rod-like spacer structure is used; hereinafter, a protein of this type is referred to as the "long type"), a histidine tag, a biotin acceptor peptide and GFP. The portion marked with a single underline is GFP; the portion marked with a double underline is the biotin acceptor peptide; the portion marked with a dotted underline is the histidine tag; the portions enclosed with boxes are linkers; and the portions without any marking represent the dynein protein whose stalk domain has been mutated.

FIG. 5 shows the amino acid sequence (SEQ ID NO:4) of a fusion protein comprising a protein based on the stalk domain of dynein having a mutation introduced thereinto (long type), a histidine tag, a biotin acceptor peptide and DsRed. The portion marked with a single underline is DsRed; the portion marked with a double underline is the biotin acceptor peptide; the portion marked with a dotted underline is the histidine tag; the portions enclosed with boxes are linkers; and the portions without any marking represent the dynein protein whose stalk domain has been mutated.

FIG. 6 shows the amino acid sequence (SEQ ID NO:5) of a fusion protein comprising the rod domain of one polypeptide chain of .alpha.-actinin, a histidine tag, a biotin acceptor peptide and GFP. The portion marked with a single underline is GFP; the portion marked with a double underline is the biotin acceptor peptide; the portion marked with a dotted underline is the histidine tag; the portions enclosed with boxes are linkers; and the portions without any marking represent the rod domain of .alpha.-actinin.

FIG. 7 is a schematic diagram showing the structure of a spacer module.

FIG. 8 shows an electrophoretic gel pattern of a spacer module purified with Ni beads (Panel A) and a diagram showing the results of an experiment examining the reactivity between a spacer module purified with Ni beads and streptavidin (Panel B).

FIG. 9 shows the results of observation of spacer modules by rotary shadowing. Arrow marks in this Figure indicate spacer modules.

FIG. 10 shows the intracellular localization of spacer module-linked fusion proteins.

FIG. 11 shows the intracellular localization of a spacer module-linked clathrin light chain and a spacer module-linked caveolin-1.

FIG. 12 shows electrophoretic gel pattern of fractions obtained from individual purification steps when a fusion protein of a spacer module and IP3R1 was purified with an Ni column. Panel A shows the results for a spacer module-fused IP3R1. Panel B shows the results for a His tag-added IP3R1. Lane 1: sample applied to the column; lane 2: those which passed through the column; lane 3: first washed fraction; lane 4: second washed fraction; lanes 5 to 8: eluted fractions.

FIG. 13 shows an electrophoretic gel pattern obtained when an extract from HEK cells was purified with a Ni column, wherein the HEK cells express clathrin light chain to which a spacer module was linked at its C terminus. In the control, a histidine tag was added instead of a spacer module.

FIG. 14 shows the observed images by rotary shadowing of clathrin molecules (triskelion) purified from a spacer module-linked clathrin light-chain expressing HEK cells using the module. Arrow marks in this Figure indicate the GFP of the spacer module. Although short type ("short" in the Figure) and long type ("long" in the Figure) spacer modules are different in length, both modules protrudes from the center of the molecule, indicating the localization of the other end of modules therein.

FIG. 15 shows the observed images by negative staining of coated vesicles purified from a spacer module-fused clathrin light-chain expressing HEK cells. Most of the particles seen under low-magnification (lower panel) are coated vesicles. Individual particles indicated with arrow marks are enlarged in the upper panel. The inserted diagram is a schematic diagram showing molecular arrangement in the coated vesicle.

FIG. 16 shows an (electrophoretic gel pattern?) of coated vesicles purified from a spacer module-fused clathrin light chain expressing HEK cells (right lane). The central lane represents clathrin molecules (triskelion) which were purified alone after solubilization. The left lane represents molecular weight marker. The fraction purified as coated vesicles contains a large number of component proteins other than clathrin.

FIG. 17 shows the intracellular localization of a cytoplasmic dynein light chain linked to a spectrin repeat type spacer module. Panel A shows the spacer module alone, and Panel B shows the spacer linked to cytoplasmic dynein light chain.

FIG. 18 shows the intracellular localization of a clathrin light chain fused to a spectrin repeat type spacer module. While no localization at a specific site is observed when the spacer module was expressed alone (Panel A), localization equivalent to that of wild-type clathrin was observed when the spacer module was fused to the clathrin light chain (Panel B).

FIG. 19 shows the amino acid sequence (SEQ ID NO:12) of a fusion protein comprising the rod domains of two polypeptide chains of .alpha.-actinin, a histidine tag, a biotin acceptor peptide and GFP. The portion marked with a single underline is GFP; the portion marked with a double underline is the biotin acceptor peptide; the portion marked with a dotted underline is the histidine tag; the portions enclosed with boxes are linkers; and the portions without any marking represent the rod domains of .alpha.-actinin.

FIGURE LEGENDS

1. Tag 2. Labeling substance 3. Rod-like spacer substance 4. Interacting substance 5. Target compound 6. Protein body

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinbelow, the present invention will be described in detail.

The molecular module of the present invention binds to a target compound and is used for purifying or labeling the compound. The molecular module of the present invention has a rod-like spacer substance, an interacting substance that interacts with the target compound, a tag and a labeling substance, wherein the interacting substance is positioned at one end of the rod-like spacer substance, and the tag and the labeling substance are positioned at the other end of the rod-like spacer substance.

The target compound is not particularly limited as long as the compound is capable of being purified or labeled by the molecular module of the present invention. Biopolymers such as protein or nucleic acid, or low molecular weight compounds binding thereto may be used widely.

The rod-like spacer substance is not particularly limited as long as the substance can take a rod-like spacer structure. Preferably, the rod-like spacer substance is a protein. Preferable examples include, but are not limited to, a protein taking an antiparallel coiled coil structure, a protein taking a spectrin repeat structure, a filamentous phage and a filamentous protein of a phage. As the protein taking an antiparallel coiled coil structure, for example, the stalk domain of dynein (a motor protein) or a protein based on the stalk domain of dynein to which an artificial mutation has been added in order to stabilize the antiparallel coiled coil structure may be given. Examples of such artificial mutation-added proteins include a protein consisting of a peptide represented by the amino acid sequence of SEQ ID NO: 6 and a peptide represented by the amino acid sequence of SEQ ID NO: 7 (short type) and a protein consisting of a peptide represented by the amino acid sequence of SEQ ID NO: 8 and a peptide represented by the amino acid sequence of SEQ ID NO: 9 (long type). In these examples, the length of the long type rod-like spacer structure is 150% of the length of the short type rod-like spacer structure. In addition to the above-listed examples, antiparallel coiled coil structures may be prepared based on the disclosure in Current Opinion in Structural Biology 2001, 11:450-457 and so forth. As the protein taking a spectrin repeat structure, for example, the rod domain of .alpha.-actinin or a protein based on the rod domain of .alpha.-actinin into which an artificial mutation has been added to stabilize the spectrin repeat structure may be given. Examples of the rod domain of .alpha.-actinin include a protein represented by the amino acid sequence of SEQ ID NO: 10 and a protein consisting of a peptide represented by the amino acid sequence of SEQ ID NO: 13 and a peptide represented by the amino acid sequence of SEQ ID NO: 14. In the latter protein consisting of two peptides, the labeling substance or the like is inserted between the two peptides. Examples of filamentous phage include fl phage, fd phage and M13 phage. The rod-like spacer substance may be a substance other than protein. Examples of such non-proteinaceous substances include, but are not limited to, carbon nanotube, carbon nanohorn and amylose.

The length and the diameter of rod-like spacer substance are not particularly limited as long as an appropriate distance can be secured between the target compound and the tag/the label. The length is preferably 5-50 nm, more preferably 10-30 nm. The diameter is preferably 1-10 nm, more preferably 2-5 nm.

The interacting substance may be any substance as long as it interacts with the target substance. Proteins and low molecular weight ligands may be given. The interacting substance may be selected depending on the type of the target compound. For example, when the target compound is a protein, the interacting substance may be an antibody that recognizes the protein; when the target compound is an antibody, the interacting substance may be an antigen that the antibody recognizes; when the target compound is a receptor, the interacting substance may be a ligand for the receptor; and when the target compound is a ligand, the interacting substance may be a receptor for the ligand.

The tag may be a conventional tag used in protein purification. Specific examples of such tag include, but are not limited to, histidine tags, biotin acceptor peptides (e.g., a peptide represented by the amino acid sequence of SEQ ID NO: 11), polyarginine and FK506 binding protein (FKBP). One or more tags may be used in the molecular module. When the target compound is a protein, the tag may be inserted into the protein. The site of tag insertion is not particularly limited as long as the insertion does not impair the function of the protein used as a target compound. When the protein takes a loop structure, it is preferable to insert the tag into the loop. The insertion site in a loop structure may be, for example, between amino acid residues 173 and 174 of GFP or between amino acid residues 170 and 171 of DsRed.

The labeling substance may be a conventional substance generally used for labeling biomolecules. Examples of such labeling substance include, but are not limited to, fluorescent substances, dyes, heavy metal compounds, heavy metal colloids and oxidoreductases. Preferably, the labeling substance is proteinaceous. More preferably, a fluorescent protein is used. As a preferable fluorescent protein, GFP (Aequorea victoria green fluorescence protein) or DsRed (Discosoma sp. red fluorescence protein) may be given. Other then these fluorescent proteins, variants of GFP such as enhanced green fluorescence protein (EGFP), yellow fluorescence protein (YFP), enhanced yellow fluorescence protein (EYFP), cyan fluorescence protein (CFP), enhanced cyan fluorescence protein (ECFP), blue fluorescence protein (BFP) and enhanced blue fluorescence protein (EBFP), as well as variants of DsRed such as monomeric Banana yellow fluorescence protein (mBanana), monomeric Orange fluorescence protein (mOrange), monomeric Tangerine fluorescence protein (mTangerine), monomeric Strawberry red fluorescence protein (mStrawberry) and monomeric Cherry red fluorescence protein (mCherry) may also be used. Alternatively, a non-proteinaceous fluorescent substance may be used as a labeling substance. For example, fluorescein, Rhodamine, eosin or NBD fluorescent substances, or the like may be used. Specific examples include, but are not limited to, fluorescein-5-isothiocyanate, diacyl (such as isobutyryl, acetyl or pivaloyl) fluorescein-5 and/or 6-carboxylic acid pentafluorophenyl ester, 6-(diacyl-5 and/or 6-carboxamide-fluorescein)aminohexanoic acid pentafluorophenyl ester, Texas Red (Trademark of Molecular Probes, Inc.), tetramethylrhodamine-5 (and 6) isothiocyanate, oesin-isothiocyanate, erythrosin-5-isothiocyanate, 4-chloro-7-nitrobenz-2-oxa-1,3-diazole, 4-fluoro-7-nitrobenz-2-oxa-1,3-diazol, 3-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)methylaminopropionitrile, 6-(7-nitrobenz-2-oxa-1,3-diazol-4-yl-aminohexanoic acid, succinimidyl 12-(N-methyl-N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)aminododecanoate, 7-diethylamino-3-(4'-isothiocyanatophenyl)-4-methylcoumarin (CP), 7-hydroxycoumarin-4-acetic acid, 7-dimethylaminocoumarin-4-acetic acid, succinimidyl 7-dimethylaminocoumarin-4-acetate, 7-methoxycoumarin-4-acetic acid, 4-acetamide-4'-isothiocyanatostilbene-2-2'-disulfonic acid (SITS), 9-chloroacridine, succinimidyl 3-(9-carbazole)propionate, succinimidyl 1-pyrenebutyrate, succinimidyl 1-pyrenenonanoate, p-nitrophenyl 1-pyrenebutyrate, 9-anthracenepropionic acid, succinimidyl anthracene-9-propionate and 2-anthracenesulfonyl chloride.

The three members of the molecular module of rod-like spacer substance, tag and labeling substance may be in the form of a fusion protein consisting of one polypeptide chain. In this case, when the interacting substance is a low molecular weight ligand, this substance may be covalently bonded through an active group located at the end of the rod-like spacer substance (e.g., .alpha.-amino group of N-terminal amino acid, carboxyl group of C-terminal amino acid, or thiol group of cystein residue). When the interacting substance is a protein, it is also possible to prepare a fusion protein of four members including the interacting substance.

The molecular module of the present invention is used for purifying and labeling a target compound. Specifically, the molecular module may be used for the following purposes.

(1) Purification of Biological Components

When the molecular module of the present invention is added to a crude extract from a biological component, one end of the molecular module specifically binds to the biological component of interest to thereby form a complex. This complex may be recovered with resin beads or magnetic beads through the tag in the module. At the time of recovery, the target for purification may be purified alone or as the complex, or even as a still larger substance (such as intracellular organelle or cell as a whole) by adding to the solution salts or surfactants as the purpose demands.

(2) Labeling at the Time of Microscopic Observation

By using a fluorescent substance as the labeling substance, microscopic observation of fluorescence signals makes it possible to indicate the localization of the target compound in cells or intracellular organelles or to trace the kinetics of the target compound in vivo. Further, by immunoelectron microscopy using an appropriate gold colloid that binds to the tag, it is also possible to explore the ligand binding site in tissue samples. Furthermore, since the molecular module of the present invention has a unique shape with a spherical portion at the end of its rod, it is believed possible to show the binding domain in protein molecules or complexes directly with the use of high resolution electronmicroscopic images.

The positional arrangement of a rod-like spacer substance, an interacting substance, a tag and a labeling substance is, for example, as shown in FIG. 1 (A). The interacting substance [4] is positioned at one end of the rod-like spacer substance [3], and the tag [1] and the labeling substance [2] are positioned at the other end. Although the tag [1] is binding to the labeling substance [2] in this Figure, the tag may be binding to the rod-like spacer substance [3] directly. Alternatively, other arrangement opposite to this Figure may be taken in which the tag [1] is binding to the rod-like spacer substance [3] directly and the labeling substance [2] is binding to the tag [1]. With such arrangements, it is possible to retain a specific distance between the target compound [5] and the tag [1]/the labeling substance [2], which leads to elimination of various adverse effects resulting from the neighboring of these substances.

The tag and label-fused protein of the present invention has a protein body, a rod-like spacer substance, a tag and a labeling substance, wherein the protein body is positioned at one end of the rod-like spacer substance, and the tag and the labeling substance are positioned at the other end of the rod-like spacer substance.

The rod-like spacer substance, the tag and the labeling substance of the tag and label-fused protein of the present invention may be the same as those substances used in the molecular module of the present invention. Further, the positional arrangement of these substances may be the same as the arrangement in the molecular module (FIG. 1 (B)). The protein body is not particularly limited. For example, a protein playing an important role in the body, such as receptor protein, may be used. All of the rod-like spacer substance, the tag and the labeling substance are preferably a protein. More preferably, these substances and the protein body form a fusion protein consisting of one polypeptide chain. Specific examples of such fusion proteins are given in FIGS. 2 to 6 (SEQ ID NOs:1-5) and FIG. 19 (SEQ ID NO:12) (however, the protein body is not included therein). FIG. 2 shows the amino acid sequence (SEQ ID NO:1) of a fusion protein in which a protein based on the stalk domain of dynein having a mutation introduced thererinto (short type) is used as a rod-like spacer substance; a histidine tag and a biotin acceptor peptide are used as tags; and GFP is used as a labeling substance. FIG. 3 shows the amino acid sequence (SEQ ID NO:2) of a fusion protein in which a protein based on the stalk domain of dynein having a mutation introduced thereinto (short type) is used as a rod-like spacer substance; a histidine tag and a biotin acceptor peptide are used as tags; and DsRed is used as a labeling substance. FIG. 4 shows the amino acid sequence (SEQ ID NO:3) of a fusion protein in which a protein used as a rod-like spacer substance; a histidine tag and a biotin acceptor peptide are used as tags; and GFP is used as a labeling substance. FIG. 5 shows the amino acid sequence (SEQ ID NO:4) of a fusion protein in which a protein based on the stalk domain of dynein having a mutation introduced thereinto (long type) is used as a rod-like spacer substance; a histidine tag and a biotin acceptor peptide are used as tags; and DsRed is used as a labeling substance. FIG. 6 shows the amino acid sequence (SEQ ID NO:5) of a fusion protein in which the rod domain of one polypeptide chain of .alpha.-actinin is used as a rod-like spacer substance; a histidine tag and a biotin acceptor peptide are used as tags; and GFP is used as a labeling substance. FIG. 19 shows the amino acid sequence (SEQ ID NO:12) of a fusion protein in which the rod domains of two polypeptide chains of .alpha.-actinin are used as a rod-like spacer substance; a histidine tag and a biotin acceptor peptide are used as tags; and GFP is used as a labeling substance. The amino acid sequences as shown in FIG. 2, FIG. 3, FIG. 4, FIG. 5, FIG. 6 and FIG. 19 are also shown in SEQ ID NOS: 1, 2, 3, 4, 5 and 12, respectively.

The method of protein purification of the present invention is characterized by comprising the following steps: (i) a step of expressing a fusion protein-encoding DNA in a cell, wherein the fusion protein has a protein body, a rod-like spacer substance, a tag and a labeling substance, the protein body being positioned at one end of the rod-like spacer substance, and the tag and the labeling substance being positioned at the other end of the rod-like spacer substance; (ii) a step to homogenize the cell and contacting the resultant homogenate with a substance having affinity to the tag; and (iii) a step of collecting the fusion protein bound to the substance having affinity to the tag.

This method of protein purification is one application of the tag and label-fused protein of the present invention. It should be noted here that this method may be performed in the same manner as conventional purification methods for tagged proteins except that a tag and a labeling protein are added through a rod-like spacer protein.

EXAMPLES

Hereinbelow, the present invention will be described more specifically with reference to the following Examples.

Example 1

Design of Spacer Modules

Proteins consisting of the amino acid sequences as shown in FIG. 2 (SEQ ID NO:1) and FIG. 4 (SEQ ID NO:3), respectively, were designed (hereinafter, these proteins are called "spacer modules"). The spacer module has GFP, a histidine tag (8.times.His), a biotin acceptor peptide (biotin acceptor domain; BAD) and a protein taking an antiparallel coiled coil structure. FIG. 7 shows a schematic diagram of the structure of this spacer module. His-tag and a biotin acceptor domain are inserted into the loop domain of GFP (173-174); a protein taking an antiparallel coiled coil structure is added to the N-terminus and the C-terminus of GFP. The protein taking an antiparallel coiled coil structure is based on the stalk domain of cytoplasmic dynein. In order to improve stability, an artificial mutation has been introduced into the stalk domain. The protein taking an antiparallel coiled coil structure is different between the spacer module shown in FIG. 2 (SEQ ID NO:1) and the spacer module shown in FIG. 4 (SEQ ID NO:3). The former uses a short type rod-like spacer structure, and the latter uses a long type rod-like spacer structure.

Further, similar spacer modules were also designed using DsRed instead of GFP (FIG. 3 and FIG. 5) (SEQ ID NO:2 and SEQ ID NO:4, respectively).

Example 2

Purification of Spacer Modules with Ni Beads

cDNA fragments encoding the four types of spacer modules designed in Example 1 were inserted into pCold vectors separately and allowed mass expression in Escherichia coli (GFP-short, DsRed-short, GFP-long and DsRed-long). The cells were homogenized, and the supernatant was bound to Ni beads. The resultant beads were washed with a solution containing 20 mM imidazole and eluted with 300 mM imidazole. The eluted fraction was subjected to SDS-PAGE. The results are shown in FIG. 8A.

Since every spacer module was detected as a single band, it was demonstrated that the histidine tag is functioning as a tag for purification. It was predicted that the rod-like portion of the short type spacer module is 16 nm long, and that portion of the long type spacer module is 24 nm long.

Example 3

Detection of Biotinylation with Streptavidin HRP

After SDS polyacrylamide-gel electrophoresis, the spacer modules purified with Ni beads were transferred onto a PVDF membrane, followed by blotting with streptavidin HRP. The results are shown in FIG. 8B.

Every spacer module reacted with streptavidin, showing that every spacer module was biotinylated.

Example 4

Observation of Morphology of Spacer Modules by Rotary Shadowing

The cDNA fragment encoding each of the above-described spacer modules was inserted into pCold TF vector and expressed as a fusion protein with trigger factor (an E. coli protein). The fusion protein was purified and observed by rotary shadowing. The results are shown in FIG. 9.

Both short type and long type spacer modules showed a dumbbell-like structure. The rod-like portion between spherical structures was longer in long type spacer modules. This is consistent with the above-mentioned prediction.

Example 5

Intracellular Localization of Spacer Module-Fused Proteins

Spacer module (GFP-short), alone or in the form of fusion proteins with other proteins, was expressed in HeLa cells, followed by detection of the intracellular GFP fluorescence. Micrographs showing the intracellular localization of the spacer module when expressed alone, when expressed as a fusion protein with a clathrin light chain (C-terminal fusion), when expressed as a fusion protein with caveolin-1 (N-terminal fusion) and when expressed as a fusion protein with ryanodine receptor 1 (RyR1) (internal insertion, 1379-1380) are given in FIG. 10A, FIG. 10B, FIG. 10C and FIG. 10D, respectively.

When the spacer module was expressed alone, the spacer module was evenly dispersed within the cell other than the nucleus. When expressed as a fusion protein with a clathrin light chain or caveolin-1, the spacer module was localized as dots around the nucleus and in the cytoplasm. When expressed as a fusion protein with RyR1, the spacer module was localized in a mesh-like manner within the cell, which is consistent that the spacer module was present in endoplasmic reticulum. In any of the fusion proteins tested, the localization pattern was consistent with the endogenous protein. Thus, it was suggested that the spacer module does not affect the structure or function of a protein when fused thereto.

Example 6

Double Staining with Different Spacer Modules

A fusion protein in which GFP-short is fused to the C-terminus of a clathrin light chain and a fusion protein in which DsRed-short is fused to the N-terminus of caveolin-1 were expressed in HeLa cells, followed by observation of cells expressing both proteins. The results are shown in FIG. 11.

Although both fusion proteins were localized in dotted manner around the nucleus and in the cytoplasm, their distributions were different from each other.

Example 7

Example of Purification of Spacer Module-Fused Protein Expressed in Mammalian Cell (Part 1)

A DNA fragment encoding a fusion protein of GFP-short and IP3R1 (N-terminal fusion) was introduced into Flp-In T-REx HEK cells, followed by selection of cell clones expressing the fusion protein stably. After induction of expression with doxycycline, membrane fractions were prepared. IP3R1 was solubilized with CHAPS and applied to an Ni column. The column was washed with 100 mM imidazole, followed by elution with 300 mM imidazole. The proteins included in fractions from individual purification stages were separated by electrophoresis. For the purpose of comparison, IP3R1 to which a histidine tag had been added at its N-terminus was also expressed in the same manner, and the proteins included in fractions of individual purification stages were examined in the same manner. The results are shown in FIG. 12.

Since the spacer module fused protein was purified in the same manner as the histidine tag-inserted IP3R1 (N-terminus), it was revealed that the spacer module functions as a tag for purification.

Example 8

Example of Purification of Spacer Module-Fused Protein Expressed in Mammalian Cell (Part 2)

A DNA fragment encoding a fusion protein of GFP-short or GFP-long and a clathrin light chain (C-terminal fusion) was introduced into Flp-In T-REx HEK cells, followed by selection of cell clones expressing the fusion protein stably. After induction of expression with doxycycline, membrane fractions were prepared. Triskelion was extracted with 0.5 M NaCl and applied to a Ni column. The column was washed with 100 mM imidazole, followed by elution with 300 mM imidazole. The proteins contained in the 300 mM imidazole elution fraction were detected by electrophoresis. As a control, a clathrin light chain to which a histidine tag had been added at its C-terminus was expressed. The results are shown in FIG. 13.

Since a clathrin heavy chain of 160 kDa was purified together with the spacer module-fused clathrin light chain, it was revealed that clathrin was purified as a protein complex.

Example 9

Observation of Morphology of Spacer Module-Fused Clathrin Complexes by Rotary Shadowing

The clathrin complexes purified in Example 8 were observed by rotary shadowing.

The clathrin complex into which a histidine tag had been inserted at the C-terminus showed a typical triskelion structure. In the short type spacer module-fused clathrin light chain, a spherical structure corresponding to GFP was observed at a site slightly away from the center of triskelion corresponding to the C-terminus of the clathrin light chain. In the long type spacer module-fused clathrin light chain, the spherical structure corresponding to GFP and even the rod-like portion were observed at sites further away from the center of triskelion. Thus, the localization of the spacer module in the protein complexes could be confirmed.

Example 10

Example of Purification of Intracellular Organelles from spacer Module-Fused Protein Expressing Cells

A DNA fragment encoding a fusion protein of a spacer module (GFP which comprises a histidine tag and a biotin acceptor sequence and is flanked by TEV protease site on both sides) and a clathrin light chain (C-terminal fusion) was introduced into Flp-In T-REx HEK cells, followed by selection of cell clones expressing the fusion protein stably. After induction of expression with doxycycline, cells were homogenized in a solution containing 0.1 M MES, pH 6.5, 0.5 mM MgCl.sub.2 and 1 mM EGTA, followed by preparation of membrane fractions. The resultant membrane fraction was bound to streptavidin magnetic beads, washed with the above-described buffer solution and then treated with TEV protease at room temperature for 1 hr. Eluted fractions were observed with electron microscopy after negative staining. The results are shown in FIG. 15.

A great number of vesicles approximately 100 nm in diameter were observed in the eluted fraction. When enlarged, the vesicles were surrounded by soccer ball-like skeletons. It was confirmed that these vesicles represent the morphology of a typical clathrin coated vesicle.

Example 11

Example of Purification of Intracellular Organelles Comprising Spacer Module-Fused Protein Expressed in Mammalian Cell

The proteins included in the coated vesicle fraction obtained in Example 10 were separated by electrophoresis. For the purpose of comparison, triskelion obtained by extracting the above fraction with 0.5 M NaCl was purified in the same manner. The results are shown in FIG. 16.

In the coated vesicle fraction, bands of a large number of other component proteins in addition to the clathrin heavy and light chains contained in triskelion were detected. The band around 27 kDa is derived from TEV protease. It was revealed that the spacer module functions effectively as a tag for purifying intracellular organelles.

Example 12

Intracellular Localization of Spectrin Repeat Type Spacer Module-Fused Protein (Part 1)

A spectrin repeat type spacer module (comprising a protein represented by the amino acid sequence of SEQ ID NO: 10), alone or in the form of a fusion protein with other protein, was expressed in HeLa cells, followed by detection of intracellular GFP fluorescence. Micrographs showing the intracellular localization of the spectrin repeat type spacer module when expressed alone and when expressed as a fusion protein with a cytoplasmic dynein light chain (TcTex-1) are given in FIG. 17A and FIG. 17B, respectively.

When the spectrin repeat type spacer module had been expressed alone, the spacer module was evenly dispersed within the cell except the nucleus. When the spacer module had been expressed as a fusion protein with a cytoplasmic dynein light chain, the spectrin repeat type spacer module was localized around the nucleus. Since its localization pattern was consistent with that of the endogenous protein, it was suggested that the spectrin repeat type spacer module does not affect the structure or function of a protein when fused thereto.

Example 13

Intracellular Localization of Spectrin Repeat Type Spacer Module-Fused Protein (Part 2)

A spectrin repeat type spacer module (comprising a peptide represented by the amino acid sequence of SEQ ID NO: 13 and a peptide represented by the amino acid sequence of SEQ ID NO: 14), alone or in the form of a fusion protein with other protein, was expressed in HeLa cells, followed by detection of intracellular GFP fluorescence. Micrographs showing the intracellular localization of the spectrin repeat type spacer module when expressed alone and when expressed as a fusion protein with a clathrin light chain are given in FIG. 18A and FIG. 18B, respectively.

When the spectrin repeat type spacer module had been expressed alone, the spacer module was evenly dispersed within the cell except the nucleus. When the spacer module had been expressed as a fusion protein with a clathrin light chain, the spectrin repeat type spacer module was localized in a dot-like manner around the nucleus and in the cytoplasm. It was suggested that the spectrin repeat type spacer module does not affect the structure or function of a protein when fused thereto.

The present specification encompasses the disclosure of the specification and/or drawings of Japanese Patent Application No. 2006-332530 based on which the present patent application claims priority. All publications, patents and patent applications cited herein are incorporated herein by reference in their entirety.

SEQUENCE LISTINGS

1

141539PRTArtificial SequenceDescription of Artificial Sequence fusion protein 1Val Asp Gln Leu Lys Ile Lys Val Glu Gln Leu Lys Glu Lys Val Asn 1 5 10 15Glu Leu Glu Leu Glu Asn Asp Glu Leu Lys Ala Lys Val Asp Asn Leu 20 25 30Asn Ser Lys Asn Arg Glu Leu Asp Val Lys Asn Glu Gln Ala Asn Gln 35 40 45Lys Leu Lys Gln Leu Val Gln Asp Val Gln Ala Ala Glu Ile Lys Val 50 55 60Lys Asp Ala Ser Glu Leu Gln Val Gln Leu Asp Val Arg Asn Lys Glu 65 70 75 80Ile Ala Val Gln Lys Val Lys Ala His Ala Asp Leu Glu Lys Ala Glu 85 90 95Pro Ala Ile Ile Glu Gly Ser Gly Val Ser Lys Gly Glu Glu Leu Phe 100 105 110Thr Gly Val Val Pro Ile Leu Val Glu Leu Asp Gly Asp Val Asn Gly 115 120 125His Lys Phe Ser Val Ser Gly Glu Gly Glu Gly Asp Ala Thr Tyr Gly 130 135 140Lys Leu Thr Leu Lys Phe Ile Cys Thr Thr Gly Lys Leu Pro Val Pro145 150 155 160Trp Pro Thr Leu Val Thr Thr Leu Thr Tyr Gly Val Gln Cys Phe Ser 165 170 175Arg Tyr Pro Asp His Met Lys Gln His Asp Phe Phe Lys Ser Ala Met 180 185 190Pro Glu Gly Tyr Val Gln Glu Arg Thr Ile Phe Phe Lys Asp Asp Gly 195 200 205Asn Tyr Lys Thr Arg Ala Glu Val Lys Phe Glu Gly Asp Thr Leu Val 210 215 220Asn Arg Ile Glu Leu Lys Gly Ile Asp Phe Lys Glu Asp Gly Asn Ile225 230 235 240Leu Gly His Lys Leu Glu Tyr Asn Tyr Asn Ser His Asn Val Tyr Ile 245 250 255Met Ala Asp Lys Gln Lys Asn Gly Ile Lys Val Asn Phe Lys Ile Arg 260 265 270His Asn Ile Glu Asp Gly Ser Gly His His His His His His His His 275 280 285Gly Ser Gly Ala Gly Thr Pro Val Thr Ala Pro Leu Ala Gly Thr Ile 290 295 300Trp Lys Val Leu Ala Ser Glu Gly Gln Thr Val Ala Ala Gly Glu Val305 310 315 320Leu Leu Ile Leu Glu Ala Met Lys Met Glu Thr Glu Ile Arg Ala Ala 325 330 335Gln Ala Gly Thr Val Arg Gly Ile Ala Val Lys Ala Gly Asp Ala Val 340 345 350Ala Val Gly Asp Thr Leu Met Thr Leu Ala Gly Ser Gly Ser His Gly 355 360 365Ser Gly Ser Val Gln Leu Ala Asp His Tyr Gln Gln Asn Thr Pro Ile 370 375 380Gly Asp Gly Pro Val Leu Leu Pro Asp Asn His Tyr Leu Ser Thr Gln385 390 395 400Ser Ala Leu Ser Lys Asp Pro Asn Glu Lys Arg Asp His Met Val Leu 405 410 415Leu Glu Phe Val Thr Ala Ala Gly Ile Thr Leu Gly Met Asp Glu Leu 420 425 430Tyr Lys Gly Ser Gly Ser Glu Ile Leu Asp Arg Ile Lys Pro Leu Arg 435 440 445Glu Glu Val Glu Gln Leu Glu Asn Ala Ala Asn Glu Leu Lys Leu Lys 450 455 460Gln Asp Glu Ile Val Ala Thr Ile Thr Ala Leu Glu Lys Ser Ile Ala465 470 475 480Ser Leu Lys Glu Glu Val Ala Thr Leu Ile Arg Glu Thr Glu Gln Ile 485 490 495Lys Thr Glu Ser Ser Lys Val Lys Ala Gln Val Gln Ala Leu Glu Ile 500 505 510Glu Val Lys Asp Asn Lys Thr Lys Val Val Gln Leu Glu Val Glu Val 515 520 525Ala Gln Leu Glu Ser Glu Val Lys Asp Leu Glu 530 5352519PRTArtificial SequenceDescription of Artificial Sequence fusion protein 2Val Asp Gln Leu Lys Ile Lys Val Glu Gln Leu Lys Glu Lys Val Asn 1 5 10 15Glu Leu Glu Leu Glu Asn Asp Glu Leu Lys Ala Lys Val Asp Asn Leu 20 25 30Asn Ser Lys Asn Arg Glu Leu Asp Val Lys Asn Glu Gln Ala Asn Gln 35 40 45Lys Leu Lys Gln Leu Val Gln Asp Val Gln Ala Ala Glu Ile Lys Val 50 55 60Lys Asp Ala Ser Glu Leu Gln Val Gln Leu Asp Val Arg Asn Lys Glu 65 70 75 80Ile Ala Val Gln Lys Val Lys Ala His Ala Asp Leu Glu Lys Ala Glu 85 90 95Pro Ala Ile Ile Glu Gly Ser Gly Asp Asn Thr Glu Asp Val Ile Lys 100 105 110Glu Phe Met Gln Phe Lys Val Arg Met Glu Gly Ser Val Asn Gly His 115 120 125Tyr Phe Glu Ile Glu Gly Glu Gly Glu Gly Lys Pro Tyr Glu Gly Thr 130 135 140Gln Thr Ala Lys Leu Gln Val Thr Lys Gly Gly Pro Leu Pro Phe Ala145 150 155 160Trp Asp Ile Leu Ser Pro Gln Phe Gln Tyr Gly Ser Lys Ala Tyr Val 165 170 175Lys His Pro Ala Asp Ile Pro Asp Tyr Met Lys Leu Ser Phe Pro Glu 180 185 190Gly Phe Thr Trp Glu Arg Ser Met Asn Phe Glu Asp Gly Gly Val Val 195 200 205Glu Val Gln Gln Asp Ser Ser Leu Gln Asp Gly Thr Phe Ile Tyr Lys 210 215 220Val Lys Phe Lys Gly Val Asn Phe Pro Ala Asp Gly Pro Val Met Gln225 230 235 240Lys Lys Thr Ala Gly Trp Glu Pro Ser Thr Glu Lys Leu Tyr Pro Gln 245 250 255Asp Gly Val Leu Lys Gly Glu Ile Ser His Ala Leu Lys Leu Lys Asp 260 265 270Gly Ser Gly His His His His His His His His Gly Ser Gly Ala Gly 275 280 285Thr Pro Val Thr Ala Pro Leu Ala Gly Thr Ile Trp Lys Val Leu Ala 290 295 300Ser Glu Gly Gln Thr Val Ala Ala Gly Glu Val Leu Leu Ile Leu Glu305 310 315 320Ala Met Lys Met Glu Thr Glu Ile Arg Ala Ala Gln Ala Gly Thr Val 325 330 335Arg Gly Ile Ala Val Lys Ala Gly Asp Ala Val Ala Val Gly Asp Thr 340 345 350Leu Met Thr Leu Ala Gly Ser Gly Ser His Tyr Thr Cys Asp Phe Lys 355 360 365Thr Val Tyr Lys Ala Lys Lys Pro Val Gln Leu Pro Gly Asn His Tyr 370 375 380Val Asp Ser Lys Leu Asp Ile Thr Asn His Asn Glu Asp Tyr Thr Val385 390 395 400Val Glu Gln Tyr Glu His Ala Glu Ala Arg His Ser Gly Ser Gln Ser 405 410 415Gly Ser Glu Ile Leu Asp Arg Ile Lys Pro Leu Arg Glu Glu Val Glu 420 425 430Gln Leu Glu Asn Ala Ala Asn Glu Leu Lys Leu Lys Gln Asp Glu Ile 435 440 445Val Ala Thr Ile Thr Ala Leu Glu Lys Ser Ile Ala Ser Leu Lys Glu 450 455 460Glu Val Ala Thr Leu Ile Arg Glu Thr Glu Gln Ile Lys Thr Glu Ser465 470 475 480Ser Lys Val Lys Ala Gln Val Gln Ala Leu Glu Ile Glu Val Lys Asp 485 490 495Asn Lys Thr Lys Val Val Gln Leu Glu Val Glu Val Ala Gln Leu Glu 500 505 510Ser Glu Val Lys Asp Leu Glu 5153665PRTArtificial SequenceDescription of Artificial Sequence fusion protein 3Val Asp Gln Leu Lys Ile Lys Val Glu Gln Leu Lys Glu Lys Val Asn 1 5 10 15Glu Leu Glu Leu Glu Asn Asp Glu Leu Lys Ala Lys Val Asp Asn Leu 20 25 30Asn Ser Lys Asn Arg Glu Leu Asp Val Lys Asn Glu Gln Ala Asn Gln 35 40 45Lys Leu Lys Gln Leu Val Gln Asp Val Gln Ala Val Arg Ile Lys Ser 50 55 60Gln Glu Leu Glu Val Lys Asn Ala Ala Ala Asn Asp Lys Leu Lys Lys 65 70 75 80Met Val Lys Asp Gln Gln Glu Ala Glu Lys Lys Lys Val Met Ser Gln 85 90 95Glu Ile Gln Glu Gln Leu His Lys Gln Gln Glu Val Ile Ala Asp Lys 100 105 110Gln Met Ser Val Lys Glu Asp Leu Asp Lys Ala Glu Ile Lys Val Lys 115 120 125Asp Ala Ser Glu Leu Gln Val Gln Leu Asp Val Arg Asn Lys Glu Ile 130 135 140Ala Val Gln Lys Val Lys Ala His Ala Asp Leu Glu Lys Ala Glu Pro145 150 155 160Ala Ile Ile Glu Gly Ser Gly Val Ser Lys Gly Glu Glu Leu Phe Thr 165 170 175Gly Val Val Pro Ile Leu Val Glu Leu Asp Gly Asp Val Asn Gly His 180 185 190Lys Phe Ser Val Ser Gly Glu Gly Glu Gly Asp Ala Thr Tyr Gly Lys 195 200 205Leu Thr Leu Lys Phe Ile Cys Thr Thr Gly Lys Leu Pro Val Pro Trp 210 215 220Pro Thr Leu Val Thr Thr Leu Thr Tyr Gly Val Gln Cys Phe Ser Arg225 230 235 240Tyr Pro Asp His Met Lys Gln His Asp Phe Phe Lys Ser Ala Met Pro 245 250 255Glu Gly Tyr Val Gln Glu Arg Thr Ile Phe Phe Lys Asp Asp Gly Asn 260 265 270Tyr Lys Thr Arg Ala Glu Val Lys Phe Glu Gly Asp Thr Leu Val Asn 275 280 285Arg Ile Glu Leu Lys Gly Ile Asp Phe Lys Glu Asp Gly Asn Ile Leu 290 295 300Gly His Lys Leu Glu Tyr Asn Tyr Asn Ser His Asn Val Tyr Ile Met305 310 315 320Ala Asp Lys Gln Lys Asn Gly Ile Lys Val Asn Phe Lys Ile Arg His 325 330 335Asn Ile Glu Asp Gly Ser Gly His His His His His His His His Gly 340 345 350Ser Gly Ala Gly Thr Pro Val Thr Ala Pro Leu Ala Gly Thr Ile Trp 355 360 365Lys Val Leu Ala Ser Glu Gly Gln Thr Val Ala Ala Gly Glu Val Leu 370 375 380Leu Ile Leu Glu Ala Met Lys Met Glu Thr Glu Ile Arg Ala Ala Gln385 390 395 400Ala Gly Thr Val Arg Gly Ile Ala Val Lys Ala Gly Asp Ala Val Ala 405 410 415Val Gly Asp Thr Leu Met Thr Leu Ala Gly Ser Gly Ser His Gly Ser 420 425 430Gly Ser Val Gln Leu Ala Asp His Tyr Gln Gln Asn Thr Pro Ile Gly 435 440 445Asp Gly Pro Val Leu Leu Pro Asp Asn His Tyr Leu Ser Thr Gln Ser 450 455 460Ala Leu Ser Lys Asp Pro Asn Glu Lys Arg Asp His Met Val Leu Leu465 470 475 480Glu Phe Val Thr Ala Ala Gly Ile Thr Leu Gly Met Asp Glu Leu Tyr 485 490 495Lys Gly Ser Gly Ser Glu Ile Leu Asp Arg Ile Lys Pro Leu Arg Glu 500 505 510Glu Val Glu Gln Leu Glu Asn Ala Ala Asn Glu Leu Lys Leu Lys Gln 515 520 525Asp Glu Ile Val Ala Thr Ile Thr Ala Leu Glu Lys Ser Ile Ala Ser 530 535 540Leu Arg Asn Glu Leu Gln Lys Leu Glu Asp Asp Ala Lys Asp Asn Gln545 550 555 560Gln Lys Ala Asn Glu Val Glu Gln Met Ile Arg Asp Leu Glu Ala Ser 565 570 575Ile Ala Arg Tyr Lys Glu Glu Tyr Ala Val Leu Ile Ser Glu Ala Gln 580 585 590Ala Ile Lys Ala Asp Leu Ala Ala Val Glu Ala Lys Val Lys Ser Leu 595 600 605Lys Glu Glu Val Ala Thr Leu Ile Arg Glu Thr Glu Gln Ile Lys Thr 610 615 620Glu Ser Ser Lys Val Lys Ala Gln Val Gln Ala Leu Glu Ile Glu Val625 630 635 640Lys Asp Asn Lys Thr Lys Val Val Gln Leu Glu Val Glu Val Ala Gln 645 650 655Leu Glu Ser Glu Val Lys Asp Leu Glu 660 6654645PRTArtificial SequenceDescription of Artificial Sequence fusion protein 4Val Asp Gln Leu Lys Ile Lys Val Glu Gln Leu Lys Glu Lys Val Asn 1 5 10 15Glu Leu Glu Leu Glu Asn Asp Glu Leu Lys Ala Lys Val Asp Asn Leu 20 25 30Asn Ser Lys Asn Arg Glu Leu Asp Val Lys Asn Glu Gln Ala Asn Gln 35 40 45Lys Leu Lys Gln Leu Val Gln Asp Val Gln Ala Val Arg Ile Lys Ser 50 55 60Gln Glu Leu Glu Val Lys Asn Ala Ala Ala Asn Asp Lys Leu Lys Lys 65 70 75 80Met Val Lys Asp Gln Gln Glu Ala Glu Lys Lys Lys Val Met Ser Gln 85 90 95Glu Ile Gln Glu Gln Leu His Lys Gln Gln Glu Val Ile Ala Asp Lys 100 105 110Gln Met Ser Val Lys Glu Asp Leu Asp Lys Ala Glu Ile Lys Val Lys 115 120 125Asp Ala Ser Glu Leu Gln Val Gln Leu Asp Val Arg Asn Lys Glu Ile 130 135 140Ala Val Gln Lys Val Lys Ala His Ala Asp Leu Glu Lys Ala Glu Pro145 150 155 160Ala Ile Ile Glu Gly Ser Gly Asp Asn Thr Glu Asp Val Ile Lys Glu 165 170 175Phe Met Gln Phe Lys Val Arg Met Glu Gly Ser Val Asn Gly His Tyr 180 185 190Phe Glu Ile Glu Gly Glu Gly Glu Gly Lys Pro Tyr Glu Gly Thr Gln 195 200 205Thr Ala Lys Leu Gln Val Thr Lys Gly Gly Pro Leu Pro Phe Ala Trp 210 215 220Asp Ile Leu Ser Pro Gln Phe Gln Tyr Gly Ser Lys Ala Tyr Val Lys225 230 235 240His Pro Ala Asp Ile Pro Asp Tyr Met Lys Leu Ser Phe Pro Glu Gly 245 250 255Phe Thr Trp Glu Arg Ser Met Asn Phe Glu Asp Gly Gly Val Val Glu 260 265 270Val Gln Gln Asp Ser Ser Leu Gln Asp Gly Thr Phe Ile Tyr Lys Val 275 280 285Lys Phe Lys Gly Val Asn Phe Pro Ala Asp Gly Pro Val Met Gln Lys 290 295 300Lys Thr Ala Gly Trp Glu Pro Ser Thr Glu Lys Leu Tyr Pro Gln Asp305 310 315 320Gly Val Leu Lys Gly Glu Ile Ser His Ala Leu Lys Leu Lys Asp Gly 325 330 335Ser Gly His His His His His His His His Gly Ser Gly Ala Gly Thr 340 345 350Pro Val Thr Ala Pro Leu Ala Gly Thr Ile Trp Lys Val Leu Ala Ser 355 360 365Glu Gly Gln Thr Val Ala Ala Gly Glu Val Leu Leu Ile Leu Glu Ala 370 375 380Met Lys Met Glu Thr Glu Ile Arg Ala Ala Gln Ala Gly Thr Val Arg385 390 395 400Gly Ile Ala Val Lys Ala Gly Asp Ala Val Ala Val Gly Asp Thr Leu 405 410 415Met Thr Leu Ala Gly Ser Gly Ser His Tyr Thr Cys Asp Phe Lys Thr 420 425 430Val Tyr Lys Ala Lys Lys Pro Val Gln Leu Pro Gly Asn His Tyr Val 435 440 445Asp Ser Lys Leu Asp Ile Thr Asn His Asn Glu Asp Tyr Thr Val Val 450 455 460Glu Gln Tyr Glu His Ala Glu Ala Arg His Ser Gly Ser Gln Ser Gly465 470 475 480Ser Glu Ile Leu Asp Arg Ile Lys Pro Leu Arg Glu Glu Val Glu Gln 485 490 495Leu Glu Asn Ala Ala Asn Glu Leu Lys Leu Lys Gln Asp Glu Ile Val 500 505 510Ala Thr Ile Thr Ala Leu Glu Lys Ser Ile Ala Ser Leu Arg Asn Glu 515 520 525Leu Gln Lys Leu Glu Asp Asp Ala Lys Asp Asn Gln Gln Lys Ala Asn 530 535 540Glu Val Glu Gln Met Ile Arg Asp Leu Glu Ala Ser Ile Ala Arg Tyr545 550 555 560Lys Glu Glu Tyr Ala Val Leu Ile Ser Glu Ala Gln Ala Ile Lys Ala 565 570 575Asp Leu Ala Ala Val Glu Ala Lys Val Lys Ser Leu Lys Glu Glu Val 580 585 590Ala Thr Leu Ile Arg Glu Thr Glu Gln Ile Lys Thr Glu Ser Ser Lys 595 600 605Val Lys Ala Gln Val Gln Ala Leu Glu Ile Glu Val Lys Asp Asn Lys 610 615 620Thr Lys Val Val Gln Leu Glu Val Glu Val Ala Gln Leu Glu Ser Glu625 630 635 640Val Lys Asp Leu Glu 6455812PRTArtificial SequenceDescription of Artificial Sequence fusion protein 5Glu Leu Asn Gln Glu Asn Glu Gln Leu Met Glu Asp Tyr Glu Lys Leu 1 5 10 15Ala Ser Asp Leu Leu Glu Trp Ile Arg Arg Thr Ile Pro Trp Leu Glu 20 25 30Asn Arg Ala Pro Glu Asn Thr Met Gln Ala Met Gln Gln Lys Leu Glu 35 40 45Asp Phe Arg Asp Tyr

Arg Arg Leu His Lys Pro Pro Lys Val Gln Glu 50 55 60Lys Cys Gln Leu Glu Ile Asn Phe Asn Thr Leu Gln Thr Lys Leu Arg 65 70 75 80Leu Ser Asn Arg Pro Ala Phe Met Pro Ser Glu Gly Lys Met Val Ser 85 90 95Asp Ile Asn Asn Ala Trp Gly Gly Leu Glu Gln Ala Glu Lys Gly Tyr 100 105 110Glu Glu Trp Leu Leu Asn Glu Ile Arg Arg Leu Glu Arg Leu Asp His 115 120 125Leu Ala Glu Lys Phe Arg Gln Lys Ala Ser Ile His Glu Ser Trp Thr 130 135 140Asp Gly Lys Glu Ala Met Leu Gln Gln Lys Asp Tyr Glu Thr Ala Thr145 150 155 160Leu Ser Glu Ile Lys Ala Leu Leu Lys Lys His Glu Ala Phe Glu Ser 165 170 175Asp Leu Ala Ala His Gln Asp Arg Val Glu Gln Ile Ala Ala Ile Ala 180 185 190Gln Glu Leu Asn Glu Leu Asp Tyr Tyr Asp Ser Pro Ser Val Asn Ala 195 200 205Arg Cys Gln Lys Ile Cys Asp Gln Trp Asp Asn Leu Gly Ala Leu Thr 210 215 220Gln Lys Arg Arg Glu Ala Leu Glu Arg Thr Glu Lys Leu Leu Glu Thr225 230 235 240Ile Asp Gln Leu Tyr Leu Glu Tyr Ala Lys Arg Ala Ala Pro Phe Asn 245 250 255Asn Trp Met Glu Gly Ala Met Glu Asp Leu Gln Asp Thr Phe Ile Val 260 265 270His Thr Ile Glu Glu Ile Gln Gly Leu Thr Thr Ala His Glu Gln Phe 275 280 285Lys Ala Thr Leu Pro Asp Ala Asp Lys Glu Arg Gln Ala Ile Leu Gly 290 295 300Ile His Asn Glu Val Ser Lys Ile Val Gln Thr Tyr His Val Asn Met305 310 315 320Ala Gly Thr Asn Pro Tyr Thr Thr Ile Thr Pro Gln Glu Ile Asn Gly 325 330 335Lys Trp Glu His Val Arg Gln Leu Val Pro Arg Arg Asp Gln Ala Leu 340 345 350Met Glu Glu His Ala Arg Gln Gln Gln Asn Glu Arg Leu Arg Lys Gln 355 360 365Phe Gly Ala Gln Ala Asn Val Ile Gly Pro Trp Ile Gln Thr Lys Met 370 375 380Glu Glu Ile Gly Arg Ile Ser Ile Glu Met His Gly Thr Leu Glu Asp385 390 395 400Gln Leu Asn His Leu Arg Gln Tyr Glu Lys Ser Ile Val Asn Tyr Lys 405 410 415Pro Lys Ile Asp Gln Leu Glu Gly Asp His Gln Gln Ile Gln Glu Ala 420 425 430Leu Ile Phe Asp Asn Lys His Thr Asn Tyr Thr Met Glu His Ile Arg 435 440 445Val Gly Trp Glu Gln Leu Leu Thr Thr Ile Ala Arg Thr Ile Asn Glu 450 455 460Val Glu Asn Gln Ile Leu Thr Leu Glu Gly Ser Gly Val Ser Lys Gly465 470 475 480Glu Glu Leu Phe Thr Gly Val Val Pro Ile Leu Val Glu Leu Asp Gly 485 490 495Asp Val Asn Gly His Lys Phe Ser Val Ser Gly Glu Gly Glu Gly Asp 500 505 510Ala Thr Tyr Gly Lys Leu Thr Leu Lys Phe Ile Cys Thr Thr Gly Lys 515 520 525Leu Pro Val Pro Trp Pro Thr Leu Val Thr Thr Leu Thr Tyr Gly Val 530 535 540Gln Cys Phe Ser Arg Tyr Pro Asp His Met Lys Gln His Asp Phe Phe545 550 555 560Lys Ser Ala Met Pro Glu Gly Tyr Val Gln Glu Arg Thr Ile Phe Phe 565 570 575Lys Asp Asp Gly Asn Tyr Lys Thr Arg Ala Glu Val Lys Phe Glu Gly 580 585 590Asp Thr Leu Val Asn Arg Ile Glu Leu Lys Gly Ile Asp Phe Lys Glu 595 600 605Asp Gly Asn Ile Leu Gly His Lys Leu Glu Tyr Asn Tyr Asn Ser His 610 615 620Asn Val Tyr Ile Met Ala Asp Lys Gln Lys Asn Gly Ile Lys Val Asn625 630 635 640Phe Lys Ile Arg His Asn Ile Glu Asp Ser Gly His His His His His 645 650 655His His His Gly Ser Gly Ala Gly Thr Pro Val Thr Ala Pro Leu Ala 660 665 670Gly Thr Ile Trp Lys Val Leu Ala Ser Glu Gly Gln Thr Val Ala Ala 675 680 685Gly Glu Val Leu Leu Ile Leu Glu Ala Met Lys Met Glu Thr Glu Ile 690 695 700Arg Ala Ala Gln Ala Gly Thr Val Arg Gly Ile Ala Val Lys Ala Gly705 710 715 720Asp Ala Val Ala Val Gly Asp Thr Leu Met Thr Leu Ala Gly Ser Gly 725 730 735Ser His Gly Ser Gly Ser Val Gln Leu Ala Asp His Tyr Gln Gln Asn 740 745 750Thr Pro Ile Gly Asp Gly Pro Val Leu Leu Pro Asp Asn His Tyr Leu 755 760 765Ser Thr Gln Ser Ala Leu Ser Lys Asp Pro Asn Glu Lys Arg Asp His 770 775 780Met Val Leu Leu Glu Phe Val Thr Ala Ala Gly Ile Thr Leu Gly Met785 790 795 800Asp Glu Leu Tyr Lys Gly Ser Gly Ser Glu Val Asp 805 8106102PRTArtificial SequenceDescription of Artificial Sequence synthetic peptide 6Val Asp Gln Leu Lys Ile Lys Val Glu Gln Leu Lys Glu Lys Val Asn 1 5 10 15Glu Leu Glu Leu Glu Asn Asp Glu Leu Lys Ala Lys Val Asp Asn Leu 20 25 30Asn Ser Lys Asn Arg Glu Leu Asp Val Lys Asn Glu Gln Ala Asn Gln 35 40 45Lys Leu Lys Gln Leu Val Gln Asp Val Gln Ala Ala Glu Ile Lys Val 50 55 60Lys Asp Ala Ser Glu Leu Gln Val Gln Leu Asp Val Arg Asn Lys Glu 65 70 75 80Ile Ala Val Gln Lys Val Lys Ala His Ala Asp Leu Glu Lys Ala Glu 85 90 95Pro Ala Ile Ile Glu Gly 1007102PRTArtificial SequenceDescription of Artificial Sequence synthetic peptide 7Ser Glu Ile Leu Asp Arg Ile Lys Pro Leu Arg Glu Glu Val Glu Gln 1 5 10 15Leu Glu Asn Ala Ala Asn Glu Leu Lys Leu Lys Gln Asp Glu Ile Val 20 25 30Ala Thr Ile Thr Ala Leu Glu Lys Ser Ile Ala Ser Leu Lys Glu Glu 35 40 45Val Ala Thr Leu Ile Arg Glu Thr Glu Gln Ile Lys Thr Glu Ser Ser 50 55 60Lys Val Lys Ala Gln Val Gln Ala Leu Glu Ile Glu Val Lys Asp Asn 65 70 75 80Lys Thr Lys Val Val Gln Leu Glu Val Glu Val Ala Gln Leu Glu Ser 85 90 95Glu Val Lys Asp Leu Glu 1008165PRTArtificial SequenceDescription of Artificial Sequence synthetic peptide 8Val Asp Gln Leu Lys Ile Lys Val Glu Gln Leu Lys Glu Lys Val Asn 1 5 10 15Glu Leu Glu Leu Glu Asn Asp Glu Leu Lys Ala Lys Val Asp Asn Leu 20 25 30Asn Ser Lys Asn Arg Glu Leu Asp Val Lys Asn Glu Gln Ala Asn Gln 35 40 45Lys Leu Lys Gln Leu Val Gln Asp Val Gln Ala Val Arg Ile Lys Ser 50 55 60Gln Glu Leu Glu Val Lys Asn Ala Ala Ala Asn Asp Lys Leu Lys Lys 65 70 75 80Met Val Lys Asp Gln Gln Glu Ala Glu Lys Lys Lys Val Met Ser Gln 85 90 95Glu Ile Gln Glu Gln Leu His Lys Gln Gln Glu Val Ile Ala Asp Lys 100 105 110Gln Met Ser Val Lys Glu Asp Leu Asp Lys Ala Glu Ile Lys Val Lys 115 120 125Asp Ala Ser Glu Leu Gln Val Gln Leu Asp Val Arg Asn Lys Glu Ile 130 135 140Ala Val Gln Lys Val Lys Ala His Ala Asp Leu Glu Lys Ala Glu Pro145 150 155 160Ala Ile Ile Glu Gly 1659165PRTArtificial SequenceDescription of Artificial Sequence synthetic peptide 9Ser Glu Ile Leu Asp Arg Ile Lys Pro Leu Arg Glu Glu Val Glu Gln 1 5 10 15Leu Glu Asn Ala Ala Asn Glu Leu Lys Leu Lys Gln Asp Glu Ile Val 20 25 30Ala Thr Ile Thr Ala Leu Glu Lys Ser Ile Ala Ser Leu Arg Asn Glu 35 40 45Leu Gln Lys Leu Glu Asp Asp Ala Lys Asp Asn Gln Gln Lys Ala Asn 50 55 60Glu Val Glu Gln Met Ile Arg Asp Leu Glu Ala Ser Ile Ala Arg Tyr 65 70 75 80Lys Glu Glu Tyr Ala Val Leu Ile Ser Glu Ala Gln Ala Ile Lys Ala 85 90 95Asp Leu Ala Ala Val Glu Ala Lys Val Lys Ser Leu Lys Glu Glu Val 100 105 110Ala Thr Leu Ile Arg Glu Thr Glu Gln Ile Lys Thr Glu Ser Ser Lys 115 120 125Val Lys Ala Gln Val Gln Ala Leu Glu Ile Glu Val Lys Asp Asn Lys 130 135 140Thr Lys Val Val Gln Leu Glu Val Glu Val Ala Gln Leu Glu Ser Glu145 150 155 160Val Lys Asp Leu Glu 16510473PRTArtificial SequenceDescription of Artificial Sequence synthetic protein 10Glu Leu Asn Gln Glu Asn Glu Gln Leu Met Glu Asp Tyr Glu Lys Leu 1 5 10 15Ala Ser Asp Leu Leu Glu Trp Ile Arg Arg Thr Ile Pro Trp Leu Glu 20 25 30Asn Arg Ala Pro Glu Asn Thr Met Gln Ala Met Gln Gln Lys Leu Glu 35 40 45Asp Phe Arg Asp Tyr Arg Arg Leu His Lys Pro Pro Lys Val Gln Glu 50 55 60Lys Cys Gln Leu Glu Ile Asn Phe Asn Thr Leu Gln Thr Lys Leu Arg 65 70 75 80Leu Ser Asn Arg Pro Ala Phe Met Pro Ser Glu Gly Lys Met Val Ser 85 90 95Asp Ile Asn Asn Ala Trp Gly Gly Leu Glu Gln Ala Glu Lys Gly Tyr 100 105 110Glu Glu Trp Leu Leu Asn Glu Ile Arg Arg Leu Glu Arg Leu Asp His 115 120 125Leu Ala Glu Lys Phe Arg Gln Lys Ala Ser Ile His Glu Ser Trp Thr 130 135 140Asp Gly Lys Glu Ala Met Leu Gln Gln Lys Asp Tyr Glu Thr Ala Thr145 150 155 160Leu Ser Glu Ile Lys Ala Leu Leu Lys Lys His Glu Ala Phe Glu Ser 165 170 175Asp Leu Ala Ala His Gln Asp Arg Val Glu Gln Ile Ala Ala Ile Ala 180 185 190Gln Glu Leu Asn Glu Leu Asp Tyr Tyr Asp Ser Pro Ser Val Asn Ala 195 200 205Arg Cys Gln Lys Ile Cys Asp Gln Trp Asp Asn Leu Gly Ala Leu Thr 210 215 220Gln Lys Arg Arg Glu Ala Leu Glu Arg Thr Glu Lys Leu Leu Glu Thr225 230 235 240Ile Asp Gln Leu Tyr Leu Glu Tyr Ala Lys Arg Ala Ala Pro Phe Asn 245 250 255Asn Trp Met Glu Gly Ala Met Glu Asp Leu Gln Asp Thr Phe Ile Val 260 265 270His Thr Ile Glu Glu Ile Gln Gly Leu Thr Thr Ala His Glu Gln Phe 275 280 285Lys Ala Thr Leu Pro Asp Ala Asp Lys Glu Arg Gln Ala Ile Leu Gly 290 295 300Ile His Asn Glu Val Ser Lys Ile Val Gln Thr Tyr His Val Asn Met305 310 315 320Ala Gly Thr Asn Pro Tyr Thr Thr Ile Thr Pro Gln Glu Ile Asn Gly 325 330 335Lys Trp Glu His Val Arg Gln Leu Val Pro Arg Arg Asp Gln Ala Leu 340 345 350Met Glu Glu His Ala Arg Gln Gln Gln Asn Glu Arg Leu Arg Lys Gln 355 360 365Phe Gly Ala Gln Ala Asn Val Ile Gly Pro Trp Ile Gln Thr Lys Met 370 375 380Glu Glu Ile Gly Arg Ile Ser Ile Glu Met His Gly Thr Leu Glu Asp385 390 395 400Gln Leu Asn His Leu Arg Gln Tyr Glu Lys Ser Ile Val Asn Tyr Lys 405 410 415Pro Lys Ile Asp Gln Leu Glu Gly Asp His Gln Gln Ile Gln Glu Ala 420 425 430Leu Ile Phe Asp Asn Lys His Thr Asn Tyr Thr Met Glu His Ile Arg 435 440 445Val Gly Trp Glu Gln Leu Leu Thr Thr Ile Ala Arg Thr Ile Asn Glu 450 455 460Val Glu Asn Gln Ile Leu Thr Leu Glu465 4701172PRTArtificial SequenceDescription of Artificial Sequence synthetic peptide 11Gly Ala Gly Thr Pro Val Thr Ala Pro Leu Ala Gly Thr Ile Trp Lys 1 5 10 15Val Leu Ala Ser Glu Gly Gln Thr Val Ala Ala Gly Glu Val Leu Leu 20 25 30Ile Leu Glu Ala Met Lys Met Glu Thr Glu Ile Arg Ala Ala Gln Ala 35 40 45Gly Thr Val Arg Gly Ile Ala Val Lys Ala Gly Asp Ala Val Ala Val 50 55 60Gly Asp Thr Leu Met Thr Leu Ala 65 7012810PRTArtificial SequenceDescription of Artificial Sequence fusion protein 12Thr Ile Asp Gln Leu His Leu Glu Phe Ala Lys Arg Ala Ala Pro Phe 1 5 10 15Asn Asn Trp Met Glu Gly Ala Met Glu Asp Leu Gln Asp Met Phe Ile 20 25 30Val His Ser Ile Glu Glu Ile Gln Ser Leu Ile Ser Ala His Asp Gln 35 40 45Phe Lys Ala Thr Leu Pro Glu Ala Asp Gly Glu Arg Gln Ala Ile Leu 50 55 60Ser Ile Gln Asn Glu Val Glu Lys Val Ile Gln Ser Tyr Ser Met Arg 65 70 75 80Ile Ser Ala Ser Asn Pro Tyr Ser Thr Val Thr Val Glu Glu Ile Arg 85 90 95Thr Lys Trp Glu Lys Val Lys Gln Leu Val Pro Gln Arg Asp Gln Ser 100 105 110Leu Gln Glu Glu Leu Ala Arg Gln His Ala Asn Glu Arg Leu Arg Arg 115 120 125Gln Phe Ala Ala Gln Ala Asn Val Ile Gly Pro Trp Ile Gln Thr Lys 130 135 140Met Glu Glu Ile Ala Arg Ser Ser Ile Glu Met Thr Gly Pro Leu Glu145 150 155 160Asp Gln Met Asn Gln Leu Lys Gln Tyr Glu Gln Asn Ile Ile Asn Tyr 165 170 175Lys His Asn Ile Asp Lys Leu Glu Gly Asp His Gln Leu Ile Gln Glu 180 185 190Ala Leu Val Phe Asp Asn Lys His Thr Asn Tyr Thr Met Glu His Ile 195 200 205Arg Val Gly Trp Glu Leu Leu Leu Thr Thr Ile Ala Arg Thr Ile Asn 210 215 220Glu Val Glu Thr Gln Ile Leu Thr Glu Phe Gly Ser Gly Val Ser Lys225 230 235 240Gly Glu Glu Leu Phe Thr Gly Val Val Pro Ile Leu Val Glu Leu Asp 245 250 255Gly Asp Val Asn Gly His Lys Phe Ser Val Ser Gly Glu Gly Glu Gly 260 265 270Asp Ala Thr Tyr Gly Lys Leu Thr Leu Lys Phe Ile Cys Thr Thr Gly 275 280 285Lys Leu Pro Val Pro Trp Pro Thr Leu Val Thr Thr Leu Thr Tyr Gly 290 295 300Val Gln Cys Phe Ser Arg Tyr Pro Asp His Met Lys Gln His Asp Phe305 310 315 320Phe Lys Ser Ala Met Pro Glu Gly Tyr Val Gln Glu Arg Thr Ile Phe 325 330 335Phe Lys Asp Asp Gly Asn Tyr Lys Thr Arg Ala Glu Val Lys Phe Glu 340 345 350Gly Asp Thr Leu Val Asn Arg Ile Glu Leu Lys Gly Ile Asp Phe Lys 355 360 365Glu Asp Gly Asn Ile Leu Gly His Lys Leu Glu Tyr Asn Tyr Asn Ser 370 375 380His Asn Val Tyr Ile Met Ala Asp Lys Gln Lys Asn Gly Ile Lys Val385 390 395 400Asn Phe Lys Ile Arg His Asn Ile Glu Asp Gly Ser Gly His His His 405 410 415His His His His His Gly Ser Gly Ala Gly Thr Pro Val Thr Ala Pro 420 425 430Leu Ala Gly Thr Ile Trp Lys Val Leu Ala Ser Glu Gly Gln Thr Val 435 440 445Ala Ala Gly Glu Val Leu Leu Ile Leu Glu Ala Met Lys Met Glu Thr 450 455 460Glu Ile Arg Ala Ala Gln Ala Gly Thr Val Arg Gly Ile Ala Val Lys465 470 475 480Ala Gly Asp Ala Val Ala Val Gly Asp Thr Leu Met Thr Leu Ala Gly 485 490 495Ser Gly Ser His Gly Ser Gly Ser Val Gln Leu Ala Asp His Tyr Gln 500 505 510Gln Asn Thr Pro Ile Gly Asp Gly Pro Val Leu Leu Pro Asp Asn His 515 520 525Tyr Leu Ser Thr Gln Ser Ala Leu Ser Lys Asp Pro Asn Glu Lys Arg 530 535 540Asp His Met Val Leu Leu Glu Phe Val Thr Ala Ala Gly Ile Thr Leu545 550

555 560Gly Met Asp Glu Leu Tyr Lys Gly Ser Gly Ser Val Asp Asn Gln Glu 565 570 575Asn Glu Arg Leu Met Glu Glu Tyr Glu Arg Leu Ala Ser Glu Leu Leu 580 585 590Glu Trp Ile Arg Arg Thr Ile Pro Trp Leu Glu Asn Arg Thr Pro Glu 595 600 605Lys Thr Met Gln Ala Met Gln Lys Lys Leu Glu Asp Phe Arg Asp Tyr 610 615 620Arg Arg Lys His Lys Pro Pro Lys Val Gln Glu Lys Cys Gln Leu Glu625 630 635 640Ile Asn Phe Asn Thr Leu Gln Thr Lys Leu Arg Ile Ser Asn Arg Pro 645 650 655Ala Phe Met Pro Ser Glu Gly Lys Met Val Ser Asp Ile Ala Gly Ala 660 665 670Trp Gln Arg Leu Glu Gln Ala Glu Lys Gly Tyr Glu Glu Trp Leu Leu 675 680 685Asn Glu Ile Arg Arg Leu Glu Arg Leu Glu His Leu Ala Glu Lys Phe 690 695 700Arg Gln Lys Ala Ser Thr His Glu Gln Trp Ala Tyr Gly Lys Glu Gln705 710 715 720Ile Leu Leu Gln Lys Asp Tyr Glu Ser Ala Ser Leu Thr Glu Val Arg 725 730 735Ala Met Leu Arg Lys His Glu Ala Phe Glu Ser Asp Leu Ala Ala His 740 745 750Gln Asp Arg Val Glu Gln Ile Ala Ala Ile Ala Gln Glu Leu Asn Glu 755 760 765Leu Asp Tyr His Asp Ala Ala Ser Val Asn Asp Arg Cys Gln Lys Ile 770 775 780Cys Asp Gln Trp Asp Ser Leu Gly Thr Leu Thr Gln Lys Arg Arg Glu785 790 795 800Ala Leu Glu Arg Thr Glu Lys Leu Leu Glu 805 81013235PRTArtificial SequenceDescription of Artificial Sequence synthetic peptide 13Thr Ile Asp Gln Leu His Leu Glu Phe Ala Lys Arg Ala Ala Pro Phe 1 5 10 15Asn Asn Trp Met Glu Gly Ala Met Glu Asp Leu Gln Asp Met Phe Ile 20 25 30Val His Ser Ile Glu Glu Ile Gln Ser Leu Ile Ser Ala His Asp Gln 35 40 45Phe Lys Ala Thr Leu Pro Glu Ala Asp Gly Glu Arg Gln Ala Ile Leu 50 55 60Ser Ile Gln Asn Glu Val Glu Lys Val Ile Gln Ser Tyr Ser Met Arg 65 70 75 80Ile Ser Ala Ser Asn Pro Tyr Ser Thr Val Thr Val Glu Glu Ile Arg 85 90 95Thr Lys Trp Glu Lys Val Lys Gln Leu Val Pro Gln Arg Asp Gln Ser 100 105 110Leu Gln Glu Glu Leu Ala Arg Gln His Ala Asn Glu Arg Leu Arg Arg 115 120 125Gln Phe Ala Ala Gln Ala Asn Val Ile Gly Pro Trp Ile Gln Thr Lys 130 135 140Met Glu Glu Ile Ala Arg Ser Ser Ile Glu Met Thr Gly Pro Leu Glu145 150 155 160Asp Gln Met Asn Gln Leu Lys Gln Tyr Glu Gln Asn Ile Ile Asn Tyr 165 170 175Lys His Asn Ile Asp Lys Leu Glu Gly Asp His Gln Leu Ile Gln Glu 180 185 190Ala Leu Val Phe Asp Asn Lys His Thr Asn Tyr Thr Met Glu His Ile 195 200 205Arg Val Gly Trp Glu Leu Leu Leu Thr Thr Ile Ala Arg Thr Ile Asn 210 215 220Glu Val Glu Thr Gln Ile Leu Thr Glu Phe Gly225 230 23514240PRTArtificial SequenceDescription of Artificial Sequence synthetic peptide 14Ser Val Asp Asn Gln Glu Asn Glu Arg Leu Met Glu Glu Tyr Glu Arg 1 5 10 15Leu Ala Ser Glu Leu Leu Glu Trp Ile Arg Arg Thr Ile Pro Trp Leu 20 25 30Glu Asn Arg Thr Pro Glu Lys Thr Met Gln Ala Met Gln Lys Lys Leu 35 40 45Glu Asp Phe Arg Asp Tyr Arg Arg Lys His Lys Pro Pro Lys Val Gln 50 55 60Glu Lys Cys Gln Leu Glu Ile Asn Phe Asn Thr Leu Gln Thr Lys Leu 65 70 75 80Arg Ile Ser Asn Arg Pro Ala Phe Met Pro Ser Glu Gly Lys Met Val 85 90 95Ser Asp Ile Ala Gly Ala Trp Gln Arg Leu Glu Gln Ala Glu Lys Gly 100 105 110Tyr Glu Glu Trp Leu Leu Asn Glu Ile Arg Arg Leu Glu Arg Leu Glu 115 120 125His Leu Ala Glu Lys Phe Arg Gln Lys Ala Ser Thr His Glu Gln Trp 130 135 140Ala Tyr Gly Lys Glu Gln Ile Leu Leu Gln Lys Asp Tyr Glu Ser Ala145 150 155 160Ser Leu Thr Glu Val Arg Ala Met Leu Arg Lys His Glu Ala Phe Glu 165 170 175Ser Asp Leu Ala Ala His Gln Asp Arg Val Glu Gln Ile Ala Ala Ile 180 185 190Ala Gln Glu Leu Asn Glu Leu Asp Tyr His Asp Ala Ala Ser Val Asn 195 200 205Asp Arg Cys Gln Lys Ile Cys Asp Gln Trp Asp Ser Leu Gly Thr Leu 210 215 220Thr Gln Lys Arg Arg Glu Ala Leu Glu Arg Thr Glu Lys Leu Leu Glu225 230 235 240

Claims

The invention claimed is:

1. A labeled fusion protein comprising a first protein, a rod-like spacer, a tag and a label, wherein the first protein is positioned at one end of the rod-like spacer, and the tag and the label are positioned at the other end of the rod-like spacer, wherein the rod-like spacer is a protein that has an antiparallel coiled coil structure and is composed of a first rod-like spacer domain and a second-rod like spacer domain, wherein the tag is an isolation tag for purification of the fusion protein and the label is for detecting the fusion protein, wherein the tag and label are located between the first rod-like spacer domain and the second rod-like spacer domain, and wherein the first protein, the rod-like spacer, the tag and the label form a polypeptide chain.

2. The labeled fusion protein according to claim 1, wherein the rod-like spacer is a protein that has a spectrin repeat structure.

3. The labeled fusion protein according to claim 2, wherein the tag is a histidine tag or a biotin acceptor peptide.

4. The labeled fusion protein according to claim 2, wherein the label is GFP or DsRed.

5. The labeled fusion protein according to claim 1, wherein the tag is a histidine tag or a biotin acceptor peptide.

6. The labeled fusion protein according to claim 5, wherein the label is GFP or DsRed.

7. The labeled fusion protein according to claim 1, wherein the label is GFP or DsRed.

8. A method of protein purification comprising the following steps: (i) expressing a fusion protein-encoding DNA in a cell, wherein the fusion protein comprises a first protein, a rod-like spacer, a tag and a label, wherein the first protein is positioned at one end of the rod-like spacer, the tag and the label are positioned at the other end of the rod-like spacer, and the rod-like spacer is a protein that has an antiparallel coiled coil structure and is composed of a first rod-like spacer domain and a second-rod like spacer domain, wherein the tag is an isolation tag for purification of the fusion protein and the label is for detecting the fusion protein, wherein the tag and label are located between the first rod-like spacer domain and the second rod-like spacer domain, and wherein the first protein, the rod-like spacer, the tag and the label form a polypeptide chain; (ii) homogenizing the cell and contacting the resultant homogenate with a target compound having affinity for the tag; and (iii) collecting the fusion protein bound to the target compound.

9. The method according to claim 8, wherein the rod-like spacer is a protein that has a spectrin repeat structure.

10. The method according to claim 8, wherein the tag is a histidine tag or a biotin acceptor peptide.

11. The method according to claim 8, wherein the label is GFP or DsRed.